Method and apparatus for reducing exhaust emissions during acceleration

ABSTRACT

A device for increasing the performance of diesel engines and reducing exhaust emissions during acceleration by porting highpressure air directly to the cylinders of the engine independently of the normal air supply during the compression stroke when accelerating the engine. The air is supplied to the cylinders until such a time as the normal air intake is sufficient to adequately combust the increased fuel flow.

United States Patent [1 1 3,659,415 Brenneke 451 M 2, 1972 [54] METHOD AND APPARATUS FOR 3,393,532 341968 Hubers ..l23/26 3,02 ,901 1962 Cook ....123/l19C REDUCING EXHAUST EWSSIONS 2,056,710 10/1936 Caserta 1.60/16 D DURlNG ACCELERATION 2,256,302 9/1941 Wehmeier ..60/ 1 7 72 lnvemor; Anhur Brenneke, New Came, 1 3,007,626 11/1961 Simson ....123/1 19 C [73] Assignee: TRW Inc., Cleveland, Ohio 22 17 1970 Primary Examiner-Laurence M. Goodridge [21] A I N 64 403 AnorneyHill, Sherman, Meroni, Gross & Simpson 52 us. c1; ..60/l3, 60/16, 123/119 c, TRAC 123/179 L A device for increasing the performance of diesel engines and [51 Int. Cl ..F02b 41/00 reducing exhaust emissions during acceleration by porting [58] Field of Search ..123/1 A, 26, l 19 C, 179 L; high pressure i directly to the cylinders of the engine inde 60/13 16 17 pendently of the normal air supply during the compression stroke when accelerating the engine. The air is supplied to the [56] References Clted cylinders until such a time as the normal air intake is sufficient UNITED STATES PATENTS to adequately combust the increased fuel flow. 2,995,890 8/ 1961 Dolza ..60/13 1 Claims, 1 Drawing Figure PATENTEDMAY 2 1972 N'IOK.

METHOD AND APPARATUS FOR REDUCING EXHAUST EMISSIONS DURING ACCELERATION BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to internal combustion engines and more particularly to an exhaust emission reducer and engine perfonnance booster for initial acceleration.

2. Prior Art lntemal combustion engines, and especially diesel engines, are either naturally aspirated or pressure-aspirated as by means of a super charger. In either case, the flow of air to the cylinders is insufficient at times to adequately combust all of the fuel supplied. This is especially true upon acceleration.

For example, in the case of a supercharged diesel engine, the super charger is normally run off of an exhaust driven-turbine. When the engine is initially accelerated, the flow of fuel to the cylinder is significantly increased. However, at this time, the flow of air to the cylinders through the air intake manifold remains constant. Therefore, the fuel is incompletely combusted in the cylinders until such time as the higher pressure exhaust has reached the drive turbine of the supercharger to run the supercharger at a greater speed, thereby increasing the flow of air to the cylinders. While this condition may exist for only a few seconds, during that period of time the exhaust is noticeably thicker and higher in smoke and pollutants.

It has been suggested to reduce this problem by incorporating a time delay in the fuel supply, whereby acceleration increases the fuel supply only gradually over a period of time. While this reduces the amount of unburned fuel in the cylinders and exhaust smoke, it does not eliminate the problem and it has a noticeably adverse effect upon the performance of the engine.

This is especially true in those instances where the engine is used as the power source forearth-moving equipment and the like.

It has also been suggested to augment the air supply at such times by the use of a subsidiary device to increase the air supply by the supercharger. Systems incorporating this type of control are extremely complex and do not adequately solve the problem inasmuch as the low-pressure air from the supercharger must still be introduced to the air intake manifold and thence to the cylinders. This normally takes a sufficiently greater period of time than does the introduction of the increased fuel supply to the cylinders. Therefore, such systems, although they may reduce the amount of time between initial acceleration and sufficiently complete combustion, do not significantly alleviate the problem.

It has also been known to start diesel engines by supplying high-pressure gases directly to the cylinders at the start of the power stroke. See for example my pending application titled Starting System for Diesel Engines," Ser. No; 842,901. Such systems, while providing a method and apparatus for the delivery of high-pressure gas to the cylinders of the engine, have not heretofore been used in acceleration control.

SUMMARY OF THE INVENTION This invention overcomes the disadvantages of the prior art by providing a system for supplying additional high-pressure air directly to the cylinders of an internal combustion engine during the compression stroke at the start of acceleration.

The system incorporates an engine-driven compressor and high-pressure compressed air storage tanks. A timed distributor is provided to sequentially supply high-pressure compressed air to a plurality of conduits communicating the distributor' directly to the cylinders of the engine during the compression stroke. Switching is also provided to initiate activation of the system at the start of acceleration and to terminate actuation of the system when the normal air supply to the cylinders is suflicient to combust the fuel being supplied.

In a modified fomi of the invention, a dual distributor is provided which allows the system to be used for starting the engine by providing high-pressure gas to the cylinders during the power stroke.

It is therefore an object of this invention to reduce smoke emissions from an internal combustion engine during acceleration, and to improve power response to demand.

It is a further object of this invention to provide for smoke emissions control of an internal combustion engine by providing auxiliary air directly to the cylinders of the engine during acceleration.

It is yet another and more specific object of this invention to provide a system for supplying relatively high-pressure air directly to the cylinders of an internal combustion engine at the start of acceleration.

It is yet another and more specific object of this invention to provide a combined system for starting diesel engines by porting high pressure air directly to the cylinders of the engine during the power stroke and to provide for emissions control by supplying air directly to the cylinders during the compression stroke at the start of acceleration.

BRIEF oescaumou OF THE DRAWING Other objects, features, and advantages of the invention will be readily apparent from the following description of a preferred embodiment thereof, taken in conjunction with the accompanying drawing, although variations and modifications may be efiected without departing from the spirit and scope of the novel concepts of the disclosure, and in which:

The drawing illustrates a disassembled schematic view of the starting and exhaust emissions control system of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT The FIGURE illustrates a combined starting and exhaust emission reduction system 10 according to this invention. The system 10 is used in connection with an internal combustion engine 11 generally of the diesel type. The engine 11 is illustrated schematically and is broken to include a portion of the engine block 12 which contains four cylinders 13, 14, 15, and 16, indicated by dotted lines. Each of the cylinders is connected with the air intake manifold 17 and with an exhaust manifold 18 which communicates with a supercharger 19 to drive the turbine section 20 thereof, which in turn drives the compressor section 21 which communicates with the intake manifold 17 via conduit 22. An exhaust pipe 23 carries the discharge from the turbine section of the super charger 19. Most diesel engines have the fuel supplied directly to the cylinders of the engine by means of an injection device and the amount of air necessary to combust a given amount of fuel is readily determinable. Further, the exhaust from the cylinders for any given quantity of fuel and air combusted therein is known. Therefore, the turbo-charger is designed to supply the required amount of air to the cylinders to combust the fuel being supplied, the design of the turbocharger being such that it will supply the desired amount of air from the turbine driving energy of the exhaust gases being emitted by that combination of fuel and air.

When the engine is accelerated, initially the flow of fuel to the cylinders is increased while the flow of air remains constant. This produces incomplete combustion of the increased amounts of fuel even through the amount of exhaust is slightly increased. The slight increase in the amount of exhaust is suflicient to begin to drive the supercharger at a higher rate which in turn increases the air supply to the cylinders. An equilibrium point is reached when the supercharger is supplying a sufficient amount of air to combust the fuel being supplied. This, however, produces a period of time between initial acceleration and full combustion when a significant portion of the fuel supplied to the cylinders is incompletely burned. During these times, a great deal of smoke emission is present, caused by the incomplete combustion.

To attempt to cure this problem by increasing the supply of air from the turbocharger, as by increasing the size of the turbocharger, results in supplying too much air and overall inefl'iciency during periods of stable operation. On the other hand, attempting to eliminate the problem by reducing the flow of fuel to a gradual increase during acceleration, reduces the responsiveness. Supplying auxiliary air to tlne air intake from an auxiliary source during periods of acceleration does not completely solve the problem inasmuch as there is still a time difierential between the initial increase in fuel and the corresponding increase in air. Further, a difficulty arises in that the pressure of the additional supplied air must be at least as great as the pressure of the air being supplied by the supercharger, otherwise a backflow of air will occur through the auxiliary system. On the other hand, if the auxiliary supply of air is at a pressure significantly higher than that of the air delivered by the supercharger, a backflow of air will occur into the supercharger. Supplying the auxiliary air to the turbine of the supercharger to drive the supercharger faster still allows the time delay problem in getting the air from the supercharger to the cylinders.

In my invention, I solve this problem by porting an additional supply of high-pressure air directly to the cylinders. The apparatus for accomplishing this includes an engine-driven compressor 25 having a crank case 26 and a compressor section 27, a storage tank or tanks 28 for storing compressed air, a control unit 29 for controlling the system, a distributor 30 timed to the engine for distributing the compressed air to the cylinders, and a plurality of valved ports 31 through 34 communicating with the interior of the cylinders. Individual conduits 35 through 38 communicate the distributor with the valve ports.

The distributor 30 is preferably a dual distributor having two timing sections 39 and 40 one of which is timed to supply air to the cylinders during the compression stroke while the other is timed to supply air to thecylinders during the power stroke. The, distributor may be of any standard desigrn sufficient to accomplish the desired results. In the dual distributor embodiment, a control 48 may be connected with the main control 29 as by means of electrical circuit wires 42 to control the supply of air during acceleration. The compressor 27 is connected ,to the control box 29 via a conduit 44 which supplies the high-pressure air to the control box which in turn directs it to the storage containers 28 or to conduits 45 or 41 connecting the control box 29 to the distributor 30 for supplying pressured air to the distributor.

Activation of the system for use during acceleration is initiated by a solenoid valve 48 connected to the acceleration air supply conduit 45 or to the control box 29 or both. A switch mechanism 69 controlling the valve 48, connected thereto by wires 42, is provided. The mechanism 48 is connected to a push rod 49 actuated by the accelerator pedal 70, or may be wired in parallel with suitable sensors in the fuel pump 71 or fuel line 72 in such a manneras to determine when the supply of fuel has significantly increased, thereby indicating the start of acceleration. Therefore, the supply of air to the cylinders is dependent upon the start of acceleration and because of the high pressure of the air supply, the air should reach the cylinders at approximately the same time as the fuel does.

Normal engine air supplies, such as those associated with brakes, may store air at to 6 atmospheres. My invention contemplates the use of an air storage system such as that disclosed which will supply air at much higher pressures than air brake pressure, preferably between 25 and 50 atmospheres. Because of the higher pressure utilized, the supply of air to the cylinders is practically instantaneous from the time of activation by the switch mechanism 69. Further, the system may include an outlet 55 from the compressed air storage system 28 through the control box 29 to a pressure reduction valve 56 which in turn is connected with a conduit 51 to the normal brake system of the vehicle wherebythe system of my invention can further fulfill the normal compressed air requirements of vehicles.

The need for the additional compressed air terminates as soon as the supercharger can supply sufficient air to the air intake 17 to adequately combust the increased fuel being supplied. Termination of the supply can be accomplished either by a time dela device within the switch solenoid valve 48 or by a sensing evnce which senses the presence of a sufiicient quantity of supercharger supplied air. Such a pressure-sensitive device may be include a pressure sensing device 57 positioned in the conduit 22 or in the manifold 17 and connected to the valve 48 by wires 50 coupled in an electric circuit. Alternatively, the cut-ofl could be determined by the speed of the supercharger. Valve 48 may be arranged to respond to any or all of theaforementioned signals.

In some eng'r'nes, it may be desirable tolimit maximum cylinder compression pressure. In such cases, a pressure regulator 73 shown in conduit 45, after the valve 48, may be used. The regulator is set for the maximum desired compression pressure so that when pressure in the cylinder reaches this valve, additional air can not enter the cylinder.

Additionally, the system is designed to function as a starting system for diesel engines by supplying compressed air under high pressure to the cylinders at the start of the power stroke. This is accomplished by a second portion 39 or 40 of the distributor 30 which is timed 180 out of phase with the other section of the distributor. By supplying the high pressure to the cylinders above the piston, during the power stroke, beginning at top center, the compresed air will force the piston downwardly in the cylinder, tlnereby turning over the engine until it fires. Such a system may be actuated by a driver-controlled manual valve 60, coupled with the control unit 29. In this case, air is supplied via line 41 to the distributor section which supplies air during the power stroke.

It can therefore be seen from the above that my invention provides a system for supplying pressured air to the cylinders of an engine during their compression stroke. Such air is supplied during the initial periods of acceleration independently of the normal air supply system. The supply of increased amounts of air facilitates total combustion of the fuel supply and instant power response. In a preferred form, the system is combined with a compressed air starting system for the engine with manual control for starting mode and includes switching and sensor mechanism for activau'ng the acceleration system and terminating the latter system.

Although the teachings of my invention have herein been discussed with reference to specific theories and embodiments, it is to be understood that these are by way of illustra tion only and that others may wish to utilize my invention in different designs or applications.

I claim as my invention:

1. A combirned starting and exhaust emissions reducing device for internal combustion engines which comprises: an engine-driven high-presure air compressor, a storage device for storing high-premure air from the compressor, a plurality of valves communicating to the interior of a plurality of engine cylinders independent of the normal air andfuel intakes for said cylinders, a first distributor, a second distributor, a separate conduit connecting each of said valves to said distributors, conduits connecting said storage device to said distributors, said first distributor timed to distribute high-pressure air to each of the cylinders only during the power stroke, said second distributor timed to distribute high-pressure air to each of the cylinders only during the compression stroke, said distributors actuatable only one at a time, means for actuating each of said distributors, means for actuating supply of air from the said storage device to the said distributors, means responsive to an increasedsupply of fuel to the cylinders for actuating the means to actuate the second distributor and for actuating the means to supply air to the distributors, and manually actuatable means for actuating the means to actuate said first distributor and to actuate the said means for supplying air to the distributors, and terminating means sensing the normal air supply and terminating actuation of the means to actuate the second distributor and the means to supply air to the distributors in response to a sensed increase in air supply by the normal air supply to the normal air intakes.

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1. A combined starting and exhaust emissions reducing device for internal combustion engines which comprises: an engine-driven high-pressure air compressor, a storage device for storing highpressure air from the compressor, a plurality of valves communicating to the interior of a plurality of engine cylinders independent of the normal air and fuel intakes for said cylinders, a first distributor, a second distributor, a separate conduit connecting each of said valves to said distributors, conduits connecting said storage device to said distributors, said first distributor timed to distribute high-pressure air to each of the cylinders only during the power stroke, said second distributor timed to distribute high-pressure air to each of the cylinders only during the compression stroke, said distributors actuatable only one at a time, means for actuating each of said distributors, means for actuating supply of air from the said storage device to the said distributors, means responsive to an increased supply of fuel to the cylinders for actuating the means to actuate the second distributor and for actuating the means to supply air to the distributors, and manually actuatable means for actuating the means to actuate said first distributor and to actuate the said means for supplying air to the distributors, and terminating means sensing the normal air supply and terminating actuation of the means to actuate the second distributor and the means to supply air to the distributors in response to a sensed increase in air supply by the normal air supply to the normal air intakes. 